AC 20-59

Appendix 4 AC 20-59 Page 6 2/19/68

(5) The flight returned after fifteen minutes the auxiliary hydraulic pump could not be turned off with on-off switch.

A relay was found shorted and replaced. The total time since overhaul is 2,127 hours.

3. CV-2401 AIRCRAFT MAINTENANCE INFORMATION. The following is a listing of significant maintenance difficulties that have been reported by air carriers as mechanical reliability reports from 1964 to 1967. This information may be useful in identifying additional structural inspection areas:

a. Fuselage.

During inspection, a crack 1 3/16 inches long was found in the left side beam angle in nose gear wheel. The repair was made in accordance with structural repair manual. The total aircraft time since overhaul is 13,450 hours.

(2) After takeoff, cargo door warning light came on.. Investigation revealed the "C' bin door aft hook attach bracket was broken at hole for spring attachment. Bracket replaced. The time since last inspection was 172 hours.

(3) Flight returned due to a reported air leak in the direct vision window. Aircraft was depressurized. Investigation revealed a loose window sill. Total time since overhaul 844 hours.

During preflight inspection, the doublers for the ADF pressure box were found cracked between stations 148.8 and 155.2. The stringer doublers on both sides of the ADF pressure box, P/N 340-3130812, were replaced and reinforced angles installed between doublers. Total time on aircraft was 19,332 hours.

b. Nacelles/Pylons.

During a periodic inspection, a 2½-inch crack was found in right nacelle upper inboard engine mount nacelle longeron and a 2-inch crack in upper outboard longeron. Repaired in accordance with Convair instructions. Total aircraft time since overhaul is 662 hours.

During a fleet campaign, in accordance with the manufacturer's instructions, a 3-inch crack was found in the inboard upper longeron fitting trailing edge of No. 2 nacelle.

C. Stabilizer.

On periodic inspection, a piece of skin approximately 1½ inches × 8 inches was found curled and cracked on the top side of outboard elevator hinge inspection plate. The repair was made in accordance with the manufacturer's structural repair manual.

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AC 20-59 Appendix 4 2/19/68 Page ?

CV-340T AIRCRAFT MAINTENANCE INFORMATION. The following is a listing of significant maintenance difficulties that have been reported by air cairiers as mechanical reliability reports from 1964 to 1967. This information may be useful in identifying additional structural inspection areas:

a. Fuselage.

(1) Inspection of the left-hand hydraulic equipment access door frame, P/N 340-3110601-17, during basic check period revealed a 6-inch crack at the top portion at station 109.

During check period, inspection of the right-hand floor structure brace at beltframe station 92 to floor beam revealed a crack at the lower end that attaches to the beltframe. The "f" angle brace was replaced.

(3) The windshield on the captain's side, P/N 340-3110301, cracked in flight. Windshield was replaced and aircraft returned to service. Total time since last inspection was 193 hours.

(4) An unscheduled landing was made due to the door warning light coming on at 5,000 feet. A bad connection at the belly compartment door microswitch was repaired. The total time since last inspection was 65 hours.

After twenty-five minutes of flight, the aircraft returned because the cargo door warning light came on at approximately 14,000 feet. Investigation revealed the "A" bin door switch out of rig. The switch was rerigged. Total time since aircraft overhaul was 120 hours.

(6) The aircraft returned after takeoff since door warning light was on. During aircraft touchdown, light went out. The cargo pit doors were opened and closed and warning light operated satisfactorily. Aircraft was released to service.

Total time since last inspection was 318 hours.

Flight returned to departure point when door warning light Investigation revealed that the rear cargo door switch, P/N 340-3150749, was loose in the bracket under the floor. The switch was tightened and rerigged. The total time on aircraft was 32,982 hours.

During a maintenance check, a 1-inch crack was found in the right window frame, P/N 340-3110314-14, at the lower inboard The window frame was replaced. Time since overhaul was 1,241 hours.

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Appendix 4 AC 20-59 Page 8 2/19/68

(9) Flutter of the elevator as reported at 225/240 knots.

Inspection after landing revealed that the second hinge pin from the outboard end had failed. Fracture occurred at the threaded end of the pin at the last thread root.

(10) Flight returned due to loss of pressurization. Investigation revealed a hole in the upper forward cargo door seal, Convair seal P/N 340-3010603-7. Time since overhaul was 935 hours.

b. Wings.

(1) During inspection of the right and left wing interspar structure, the following lower skin Z angle stringers were found cracked:

(a) At access hole number 19 in left wing fuel cell, the aft inboard bottom Z angle stringer cracked between ribs numbers 9 and 10 at stations 189 and 211.

(b) At access hole number 20 in the left fuel cell, the forward Z angle cracked between ribs numbers 9 and 10 at stations 253 and 275.

(c) In the right wing fuel cell at access hole number 19, the forward and aft Z angle stringers inboard cracked between ribs numbers 9 and 10 at stations 189 and 211.

(d) The lower forward and aft outboard Z angle stringers cracked between ribs numbers 9 and 10 at stations 189 and 211.

(e) At right wing access hole number 20, the lower forward and aft outboard Z angle stringers cracked between ribs numbers 12 and 13 at stations 253 and 275.

All cracks in the stringers in right and left wing were less than 2 inches long except outboard stringer in right wing at access hole number 20. This crack was 3 3/8 inches in length. All stringers were repaired in accordance with the manufacturer's structural repair manual. Total time on aircraft is 21,175 hours.

During preflight inspection, a fuel leak was noted in the left wing front spar area. Investigation revealed a 1 1/4-inch crack in the front spar lower rail at wing station 249½. Crack extended from the edge of the forward tang up to the first rivet on the vertical leg. Inspection of the right wing revealed a 4-inch crack in front spar lower spar rail forward tang extending from edge to the screw hole at station 2464. The total time on the airframe is 25,131 hours. The total time since Par 4

AC 20-59 Appendix 4 2/19/68 Page 9

(3) During a maintenance check, a crack was found in the left wing lower skin at station 163. The crack emitted from the outboard rivet in the forward outboard finger of inspection plate number 15 cutout doubler and extended approximately 2½ inches chordwise. A doubler was installed per Convair structural repair manual. A fleet inspection was conducted on all aircraft for similar failure. Total time on aircraft is 25,282 hours.

(4) The left elevator tab skin was found cracked on the top surface at the outboard push/pull rod attach point. The crack was approximately 1 inch aft of the tab front spar. Three rivets were found loose and one rivet was missing in the front spar at the point where the tab push/pull rod attach fitting support brackets are located. Tab P/N 9015021-1 was replaced. Manufacturer developing modification for the tab. Inspection of tabs will be conducted in accordance with manufacturer's recommendations.

(5) During a maintenance check, a crack was found in the right flap station 2 lower track support fitting, P/N 340-7310313-14, forward of the rear spar. The crack ran vertically from the top of the fitting through the 2 rear rivets for approximately 1¼ inches. The track support fitting was replaced.

(6) During a special elevator inspection, the left horizontal stabilizer new spar web was found to have several small cracks at station 150.3 where the short push/pull rod to the idler bracket attaches. The angles, P/N 9015079-99 and 9015079-101, were also cracked to the extent that several small pieces were separated from the main body. Total aircraft time since overhaul is 3,161 hours.

C• Nacelles/Pylons.

During inspection, a longitudinal crack was found on right nacelle bottom outboard longeron extending aft 7 inches from nacelle station 155. Repairs made in accordance with the Ince me th 53, 526 manufacturer's repair manual. Total aircraft time is 33,526 hours.

(2) During maintenance check, the lower inboard nacelle longeron ста на ароні тату in the left nacelle was found to be cracked in the Z angle, P/N 340-6210316-7, just above the center hinge bracket. The crack was approximately 1½ inches long and running chordwise.

d. Hydraulic Fluid.

(1) During flight, pilot reported hydraulic fluid quantity indication dropping. Investigation revealed A/C hydraulic pump warning switch leaking. Replaced warning switch.

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AC 20-59 CH 1 Appendix 5 8/24/72 Page 1 * APPENDIX 5. MODEL 240 AND 600/240D (STC # SA 1054 WE) SERIES AIRCRAFT.

1. LANDING GEAR.

a . Main Landing Gear Drag Strut.

(1) Cracks have been reported in the upper drag struts at the center pivot point.

(2) Refer to Service Engineering Report 67-240-38/2D-18 dated 6 March 1967.

b. Nose Landing Gear Drag Strut.

(1) Two instances have been reported where the upper left hand nose landing gear drag strut had fatigued and cracked. The crack originated in a sharp edge at the intersection at the side of the strut and the bottom of a defect.

(2) Refer to Service Engineering Report 15-4-240-17 dated 4 April 1960.

c. Nose Landing Gear Strut Outer Cylinder.

(1) Cracks have been found in the nose landing gear strut outer cylinder.

(2) Refer to Service Bulletin No. 32-2 dated 22 February 1968.

d. Nose Landing Gear Uplock Quadrant.

(1) Investigation following a nose landing gear retracted landing indicated that a lug failed on the P/N 240-5250109-6 uplock quadrant.

(2) Refer to Service Bulletin No. 32-3 dated 13 August 1969.

e. Nose Landing Gear Axle Cracks.

(1) Cracks have been reported in nose landing gear axle.

(2) Refer to Service Airgram 178A dated 5 April 1957. * Par l

Par 2 (2) Refer to Service Bulletin 240-413 dated 13 April 1951. * (1) e. Cracks at Corners (2) Refer to Service Bulletin No. 53-4 dated 20 November 1970. d. Cabin Windows. (2) Refer to Service Bulletins No. 52-2 dated 18 June 1970 and (1) Cockpit direct vision window fixed frames have been found Forward Direct Vision Window. (2) Refer to Service Bulletin No. 53-4 dated 20 November 1970. (1) b. Windows. (2) Refer to Service Engineering Report 6820/64-240-27 dated a. Cockpit Area Skin Cracks. *2. FUSELAGE. Page 2 Appendix 5 window openings. Cracks have been discovered at the corners of the door and of Door and Window Openings. have been experienced. Cracks, delamination, and vinyl separation of the cabin windows No. 53-3 dated 17 August 1970. cracked at the corners. Invest fet expot to of nap slidi lode. failures indicated 12 June 1964. window opening. extending aft from the lower aft corner of the pilots sliding in the upper row of rivets in the horizontal skin splice Skin cracks have been experienced originating at rivet holes

AC 20-59 CH 1 Appendix S 8/24/72 Page 3 *3. EMPENNAGE.

Horizontal Stabilizer Spar Fitting.

(1) One operator has reported finding a left hand stabilizer front spar upper attach fitting with the forward lug broken.

(2) Refer to Service Engineering Report 66-240-36/2D-6.

b. Horizontal Stabilizer Front and Rear Spar Upper Fittings.

(1) One Model 600 Dart operator has reported both subject fittings found cracked on one horizontal stabilizer.

(2) Refer to Service Bulletin 240-448A dated 5 May 1954, Service Bulletin No. A55-1 dated 25 October 1968 and Service Engineering Report 057-0/66-240-36/20-6 dated 6 July 1966.

c. Rudder Stop.

Excessive pressure exerted during ground operations has deflected the rudder stop structure.

(2) Refer to Service Bulletin 240-187 dated 2 December 1948.

4. WING.

a. Lower Surface Skin at Station 3.

Several instances have been noted where wing skins have developed cracks at Station 3.

(2) Refer to Service Engineering Report 15-4-240-6 dated 12 May 1958.

b. Lover Surface Skin Stations 1 - 5.

(1) Cracks have been noted in the wing lower surface skins around the access doors from Stations 1 to 5.

(2) Refer to Service Bulletin 240-435 dated 11 October 1957.

c. Lower Surface Skin - Station 7.

(1) Skin cracks have been experienced during inspection of wing lower surface skin at Station 7.

(2) Refer to Service Bulletin 240-437 dated 28 November 1952.

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Appendix 5 AC 20-59 CH 1 Page 4 8/24/72 * d. Lower Surface Skin.

(1) Cracks have appeared 6 to 8 inches inboard from Station 8 on the inboard end of lower skin.

(2) Refer to Service Bulletin No. A57-2A dated 22 April 1968.

e. Lower Surface Skin.

(1) One operator has reported cracks in the lower surface wing skin at the aft inboard corner of the wing main fuel tank, just outboard of Station 8.

(2) Refer to Service Bulletin No. 57-3 dated 22 January 1971.

f. Bulkhead Rails Stringer Attachment.

(1) The bulkhead rail stringer attachment in the fuel tank area is susceptible to damage due to fuel surge loads imposed during flight.

(2) Refer to Service Bulletin 240-400B dated 13 November 1952.

g. Trailing Edge Lower Surface - Center Section.

(1) Under certain conditions, flap operation and flight vibrations may cause the trailing edge channel to roll and damage the skin around the rivets and screws.

(2) Refer to Service Bulletins 240-58 and 240-224 dated 30 December 1948 and 3 November 1949.

h. Upper Surface Scuff Shield - Model 600(240D) Only.

Operators report abrasion of the wing upper surface where the engine tail pipe insulating blanket extends beyond the edges of the existing scuff shield.

(2) Refer to Service Engineering Report 67-600-37/640-38 dated 28 June 1967.

1. Corrosion of Station 8 Upper Surface Splice Plate.

(1) Corrosion has been reported on the Station 8 upper surface splice plate.

(2) Refer to Convair Liner Newsletter Volume 1, No. 8 dated March 1966. *

AC 20-59 CH 1 Appendix 5 8/24/72 Page 5 *5. NACELLE.

a. Upper Longeron - Model 240 Only.

(1) Several instances of nacelle upper longerons broken have been reported.

(2) Refer to Service Engineering Report 15-4-240-5 dated 23 Apr 11 1958.

b. After Body Vertical Beam - Model 240 Only.

(1) Failures have been noted on the nacelle after body vertical beam.

(2) Refer to Service Bulletin 240-221 dated 17 February 1949.

c. Side Cowl Inner Skin - Model 240 Only.

(1) Cracks have been noted on the engine side cowl panels at the ends of the reinforcing beads in the cowl inner skin.

(2) Refer to Service Bulletin 240-66A dated 11 January 1949.

d. Oil Filler Access Door - Model 600(240D) Only.

(1) The oil filler door bows out in flight leading to early failure.

(2) Refer to Service Bulletin No. 54-1 dated 7 April 1966.

e. Cracks in Engine Mount Fittings.

(1) Cracks and loose fasteners have been found on the engine mount fittings.

(2) Refer to Service Bulletin 240-326 dated 14 March 1950. * Par 5

AC 20-59 CH 1 Appendix 6 8/24/72 Page 1 * APPENDIX 6. MODEL 340/440 AND 640/340D/440D ( SIC # AS 1096 WE) SERIES AIRCRAFT

1. LANDING GEAR.

a. Main Landing Gear and Nose Landing Gear Drag Strut Pivot Bolts.

(1) The possibility of cracks developing in bolts presently in service can be reduced by chamfering all of the lube hole terminals.

(2) Refer to Service Engineering Report 6820/64-340-50/440-50 dated 14 February 1964.

b. Main Landing Gear Apex Bolt Menasco P/N 528076.

(1) Several reports have been received concerning cracks in the main landing gear apex bolt.

(2) Refer to Service Engineering Report 6820-340-46/440-46 dated 28 August 1962.

c. Main Landing Gear Actuating Cylinder Rod and Piston.

(1) Recently several operators have reported cracks and/or failures of P/N 340-5150117-13 retaining screw. Failure was of a fatigue nature.

(2) Refer to Service Engineering Report 15-4-34012A/440-11A dated 10 May 1965.

d. Main Landing Gear Drag Strut.

(1) Operators have experienced cracks in the upper drag struts . at the center pivot point.

(2) Refer to Service Engineering Report 057-0/67-340-62/440-61 dated 6 March 1967.

e. Nose Landing Gear Drag Strut.

(1) Cracks have developed in the nose landing gear drag strut at an external sharp corner.

(2) Refer to Service Engineering Report 15-4-340-44A/440-44A dated 16 June 1961 and Service Engineering Report 15-4-340-38/440-38 dated 4 April 1960. * Par 1

Appendix 6 AC 20-59 CHi Page 2 8/24/72

f. Nose Landing Gear Strut Outer Cylinder.

(1) Cracks have been found in the nose landing gear strut cylinders.

(2) Refer to Service Bulletin No. 32-1 dated 22 February 1968.

g. Nose Landing Gear Uplock Quadrant.

(1) Investigation following a nose landing gear retracted landing indicated that a lug failed on the P/N 240-5250109-6 uplock quadrant.

(2) Refer to Service Bulletin No. 32-2 dated 13 August 1969.

h. Main Landing Gear Axle.

(1) Cracks have been found in the main landing gear axle.

(2) Refer to Service Bulletin No. 32-3 dated 31 October 1969.

1. Nose Landing Gear Axle Cracks.

(1) Cracks have been found by the operators in the nose landing gear axles.

(2) Refer to Service Airgram 178A dated 5 April 1957.

2. FUSELAGE.

a. Cockpit Area Skin.

(1) Cracks have been reported in the fuselage skins immediately aft of the cockpit sliding window.

(2) Refer to Service Engineering Report 6820/64-340-53/440-53 dated 12 June 1964.

b. Striker Bolt Channel and Main Entrance Door Interlock Hook.

(1) Operators have reported that deflection of the main entrance door striker bolt P/N NAS 428 H 5-14 when it contacts the interlock hook resulted in failure of the hooks to engage.

Refer to Service Engineering Report 15-4-340-16/440-19 dated 21 April 1958.

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AC 20-59 CH 1 Appendix 6 8/24/72 Page 3 * c. Skin Cracks - Doors.

(1) Fuselage skin cracks have occurred adjacent to the fuselage doors and emergency exit opening.

(2) Refer to Service Bulletin No. 53-1 dated 11 September 1968.

d. Beltframe Attachment to Nose Landing Gear Wheel Well - Station 92.

(1) Operators have reported cracks in the "TEE" bracket, P/N 240-3110100-731 (LH), -732 (RH) that attaches the Station 92 beltframe to the side of the nose landing gear wheel well.

(2) Refer to Service Bulletin No. 53-4 dated 17 August 1970.

e. Windows.

(1) Investigation of a cockpit sliding window failure has indicated a need for expansion of inspection methods.

(2) Refer to Service Bulletin No. 53-5 dated 13 November 1970.

f. Windshield Lower Longeron.

(1) The windshield lower longeron connecting channel has been found cracked.

(2) Refer to Alert Service Bulletin No. 53-3 dated 27 March 1970.

g. Direct Vision Window Frames.

(1) Cracks have been found at the corners of the direct vision window frames.

(2) Refer to Service Airgram No. 225 dated 23 August 1957.

h. Corrosion of Emergency Exit Frames.

(1) Corrosion areas have been found by some operators on the emergency exit frames.

(2) Refer to Service Engineering Report 15-4-1591 dated 15 March 1960.

1. Aft Fuselage Stringers.

(1) Recent inspection of stringers in the aft fuselage has revealed numerous cracks in stringers at frame attachments.

(2) Refer to Service Bulletin No. 53-6 dated 3 March 1971.

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